Carbon pile regulator



CARBON FILE REGULATOR Filed Nov. 8, 1943 2 Sheets-Sheet 1 GD 73 73 o D60 o m M ,8 1% 7/ fir: a Q4. munumnm /3 i 5 I; I

g L w mu M u u Z 15 INVENTOR WJIImmJ Eddy M W M ATTORNEYS y 4, 1946. w.J. RADY 2,400,136

CARBON FILE REGULATOR Filed Nov. 8, 1943 2 Sheets-Sheet 2 mvEnTToRWzllmm J Eddy ATTORNEYS Patented May 14, 1946 2,400,138 CARBON PILEREGUIATOB William J. Bady, Anderson, Ind, assignor to General MotorsCorporation, Detroit, Mich, a corporation of Delaware ApplicationNovember 8, 1843, Serial No. 509,454

6 Claims.

This invention relates to regulators for electric generators by whichthe voltage of the generator is maintained within prescribed limits.More particularly the present invention relates to a carbon-pileregulator comprising a stack of carbon discs connected in the generatorfield circuit and subjected to spring pressure and electromagnetic meansresponsive to generator voltage for varying the pressure between thediscs.

It is well known that the operation of a regulator is aii'ected byvariations in the resistance of the electromagnet coil due to changes intemperature. Temperature responsive devices have been added tocompensate for this variation in resistance. An object of the presentinvention is to provide compensation without adding a temperatureresponsive compensating device. In the disclosed embodiment oi theinvention. this object is accomplished by efl'ecting, in response toincrease of temperature of the regulator, a reduction of the modulus ofelasticity of the control spring by an amount which compensatessubstantially for the increase in the resistance of the electromagnctcoil due to increase in its tempenture. In this connection, it is afurther object so to retard the transfer of heat to the spring that itwill not be heated faster than the electromagnet coil. Therefore, duringchange from environment temperature to operating temperature. thevariation in regulating voltage will beminimized.

A further object is to provide for the complete enclosure of the workingparts of the regulator in order to exclude foreign matter therefrom.while providing free relative movement between other parts due tovariations in temperature.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred embdi ment oi the present invention isclearly shown.

In the drawings:

Fig. i is a side elevation of the regulator;

F183. 2 and 8 are end views looking respectively in the directions ofarrows and 8 of Fig. 1.

F18. 4 is a side View of the armature and sprin assembly.

Fig. 6 is a longitudinal sectional view on line H of Fig. 2, and isdrawn twice the size of the preceding views.

Fig. 6 is a graph in which curves are plotted to show the eiiect ortemperature increase upon a carbon pile regulator.

Referring to Fig. 3. there is a base II to which screws Ii secure abracket I! attached by screws II to a heat-dissipating shell or radiatorit. Referring to Fig. 2, screws ll secure to the base lo t e arms it ofa clamp bracket which, b the tightening 01 a screw i1 cooperating with aout II, is caused to embrace tightly a magnetizable magnet shell 20(Fig.

Shell supports a magnetizable plate 2i carrying an adjustablemagnetizable core 12 supporting a metal tube 23 insulatingly supportinga main magnet coil 14 and an equalizer coil 25. Coil 2| is used when aplurality oi generators using similar voltage regulators are connectedwith the same storage battery.

Core 22 cooperates with armature 26 which is part of an assemblycomprising spacer 21, spring discs 28 having blades 28a. spacers 2|,metallic disc Janos-conducting discs SI of mica, and

terminal plate I! attached to legs I! of a strut 16. This assembly issecured together by screws :1 and 14. Spring blades fla'epgage eachother and the blades of the left hand disc 28 enga a ring I of copper orother 'non-magnetizable metal of good thermal conductivity.

Blades an urge the strut "against a metal disc 31 attached to a. carbonbutton I! thus placing a stack of carbon discs under compression. DiscsII are housed in a refractory tube 40 enclosed by the radiator ll. Q

The magnet housing 20 is tied-to the remote end flange ill: of radiatorN by studs 0 screwed into housing ll and having threaded ends 42a passedthrough holes in flange Ida and receiving nuts 0. Terminal plate II,attached by screws 5! to radiator I4. is insulated from the radiator Itby a non-conducting plate 5i and from the screws 82 and metal washer 0Gby insulating washers I4 and sleeves 08. Plate carries a screw itattached to a metal disc Ii, attached to a carbon button It whichreceives the pressure exerted byspring blades Ila on the stack of carbondiscs ll. Screw BI is adJustI-ble to vary the normal pressure of blades21a and the normal gap between armature it and core 12. The tubularscrew-receiving portion I of plate 50 is split at I (Fig. i) to providea screw-thread clamp which is tightened by a screw H. After screw It isad- Justed, it is covered by a cup I having an ear I attached by a screwll used to secure to plate It a wire clip I! attached to a wire 00.

The carbon stack is connected in series with the held of the generatorto be regulated. Magnet coil N is in a circuit connected across theterminalg of the generator. said circuit including a fixed resistanceunit 18 (Fig. 3) and a variable resistance unit ll controlled by aknurled disc 12.

The armature assembly is enclosed by a housin I h vin a flange Iiengaging a glass-fabriccovered metal ring I! received by a shoulder I!provided by magnet housing 20. Housing 00 has a flange I4 bearingagainst a glass-fabric-covered metal ring it received by a shoulder Itprovided by radiator I4. Housing II is resilient to provide for movementof the left end oi radiator i4 relative to magnet housing ll. 'mbe N.which expands faster than radiator ll, clears ll of housing 8| and bearsagain ll of a ring ll having resilient branches tachedto housing .0.

Screw ltsecurestoplate fltheclip "oia wire I! which passes through abushing II attached to housing II and crimped arolmd the insulation wirell.

Since the housing the iiangc the iianse ii atflistiedtothatendoiradiator II which is remote therefrom, expansion of radiator ll does notaflect the resistance 0! the carbon pile. Furthermore temperaturevariations in the carbon-pile do not materially ail'ect the pressurethereon because the materials 01 the studs 42, strut it and disc 31 areso chosen that the studs I! spend substantially the same amount as thecombination of carbon-pile, disc 31 and strut it.

The resistance of coil 24 increases as its temperature increases and itspull per volt on the armature it decreases. In order that regulation forthe same voltage may be obtained'as the temperature oi the coil Itincreases, heat from the carbon-pile causes the blades Ila to expandthereby causing their moduli of elasticity to decrease at a rate whichcompensates for the increase in resistance in the coil fl. 1n otherwords, for a given temperature increase, the coil 2| and the blades Ilabecome proportionately weaker so that the regulator, whether cold orhot, will regulate for the same voltage.-

In this connection it is important that the spring blades Ila should notbe heated faster by the carbon pile, than the coil 14 is heated by thepassage or electric current. Retardation (or transfer of heat byconduction from the carbonpiletothespringslseflectedbythesmallcrosssectional dimensions or thelegs ll oi strut SI and by the thick mica insulating disc II.

The heating of the blades as is limited due to the fact that the copperring ll is continually drawing out the heat from the blades and passingheagdto the housing II from whence it is dissipa In order to demonstratethe functions of the heat-retarding strut 8i and the heat-absorbing ringll, reference is made to Fig. 6 in which line A-B represents the voltagefor which the neulatorissetandiineA-Crepresentsthcincrease oi regulatedvoltage due to heating the mag et coil by electric current. Line a-nrepresents the decrease in regulated voltage due to increase of springtemperature. Values 0 and D are those which exist at the end 0! thewarm-up period when the dlfl'erential oi magnet coil and springtemperatures is practically constant thereafter. The ideal conditionwill exist ii line -0 is the exact opposite of line 5-0. the values Dand C being the same and the slopes ot-tlrs lines denotlng rates ofchange oi voltage due to temperature increase being the same. Thefunction of the 8H istoabsorbheatiromthespringsandtopassitontothehousingwithwhichtheringislnclocecontactinordcrsotolimittheheating of the springs that D, thefinal decrease in regulated voltage due to increase of springtemperature, will substantially equal C, the final increase in regulatedvoltage due to increase of coil temperature. The function of the strutii is so to limit the rate 0! transfer of heat from the carbon pile tothe springs that the rate oi spring temperature increase is commensuratewith the rate of coil temperature increase whereby the rate oi.regulated voltage decrease due to spring temperature increase, asreprcsaitod by A-D is commenby A-C. While the mica surate with the rateof regulated voltage increase due to coil temperature increase. asrepresented insulating disc Ii has a retarding eflect, it would not beeilective to obtain a result approaching the effect represented by A-Dwithout the strut 36 with its legs it which have relatively smallcross-sectional dimenaions and which provide relatively large radiatingsurfaces. Without the strut 38, heat from the carbon-pile would betransferred so rapidly to the springs that the decrease in regulatedvoltuse due to spring temperature increase would be that represented,for example, by dash line A-E-D with the result that, during the warmupperiod, there would be a sag in regulated voltage as represented, forexample, by dot-dash line A--F-B.

While it is known that mice will retard transier of heat, a. body oi!mica having thickness sumcient to obtain an effect approximately theeiIect represented by line A-D. could not be used since mica softenswith increase of temperature and its thickness would be substantiallyreduced under the ressure of the springs; and the distance between thecarbon-pile and the springs and the armature would be changed.

In view of the foregoing, it is apparent that the use of the metal strut38 makes it possible to use a mica disc of moderate thickness suitablefor electrical insulation. Strut 38 so retards the heat transfer to themica disc II that the softening eiIect or temperature increase thereinis negligible. A strut having a plurality o! spaced legs is relativelystrong for the amount of material used in its construction. Thecross-sectional dimensions of the legs are reduced to the minimumrequire ment of the spring pressure to be transmitted. The legs haverelatlveLv large heat-dissipating surfaces inside as well as outside sothat not all the heat in the fiat base of the strut passes into theplate 81. The strut N is therefore better adapted for the purposes oithe present invention than a tubular strut such as disclosed in myPatent No- 2,354,542 while its elongation with increase in temperaturecompensates to a material degree in compensating i'or elongation of thestuds 4!.

While the embodiment oi the present invention as herein disclosed,constitutes a preferred form. it is to be understood that other forms mht be adopted. all coming within the scope of the claims which (allow.

What is claimed is as i'ollows:

l. A carbon pile regulator comprising a housjuxtaposed carbon discsforming a stack loca within the housing; a refractory liner for aligningsaid discs; an electrode engaging one and of the stack and fixedrelative to one end of the housing; an electrode engaging the other end0! the stack and movable relative to the other end of housing: a framelocated adjacent the last mentioned end of the housing in spacedrelation thereto; an electromagnct supported by the frame; an armaturecooperating with the electromagnet and attached to the movableelectrode; biasing means for urging the armature toward the stack; amember for transmitting motion from the biasing means to the movableelectrode adiacent thereto; a flexible closure having sealin engagementwith the frame and the housing for completely enclosing the movableparts of the regulator so that same are not exposed to foreign matter;and resilient member supported by the closure and having a suspendedcentral poriion engageable with the liner to permit free movement of theliner relative to the closure.

2. A carbon pile regulator comprising a casing; a refractory tubesupported within the casing; juxtaposed carbon discs forming a stack orpile located within the tube; an electrode engaging one end of the pileand fixed relative to one end of the casing: an electrode engaging theother end of the pile and movable relative to the other end of thecasing; a frame located adjacent the last mentioned end of the casing;means for securing the frame to the casing in spaced relation thereto;an electromagnet supported by the frame; an armature cooperating withthe electromagnet and attached to the movable electrode; resilient meansoperatlvely connected with the frame and with the armature for urgingthe armature toward the pile; a member for transmitting motion from theresilient means to the movable electrode adjacent thereto; and a,flexible enclosure disposed between casing and the frame for completelyenclosing the movable parts so that same are not exposed to foreignmatter, said enclosure providing a cylindrical portion coaxial of saidtube and engageable therewith to permit free movement of the tuberelative to the enclosure.

3. A carbon pile regulator comprising a housing having one endrelatively fixed and the other end free of obstruction to elongation orcontraction due to temperature change: a stack of car bon discs locatedwithin the housing; an electrode attached to the relatively fixed end ofthe housing and engaging one end of the stack: a movable electrodeengaging the other end of the stack; a frame located adjacent the freeend of the housing: means for securing the housing to the frame inspaced relation thereto; an electromagnet supported by the frame; anarmature cooperating with the electromagnet and attached to the movableelectrode; resilient means operatively connected with the frame and withthe armature for Alrging the armature toward the pile: a member fortransmitting motion from the resilient means to the movable electrodeadjacent thereto; a pair of fabric rings one supported by the housingthe other by the frame; a flexible member disposed between the housingand the frame for completely enclosing the movable parts of theregulator so that same are not exposed to foreign matter, said enclosureproviding a cylindrical portion at each end thereof with eachcylindrical portion engaging one of the fabric rings to form effectiveseals between the enclosure and the housing and the frame.

4. A carbon pile regulator comprising a housing including a refractoryliner: said housing having one end relatively fixed and the other endfree of obstruction to elongation or contraction due to temperaturechange; a stack of carbon discs supported within the housing; anelectrode engaging one end of the stack and fixed relative to one end ofthe housing: an electrode engaging the other end of the stack andmovable relative to the other end of the housing; a frame locatedadjacent the last mentioned end of the housing in spaced relationthereto; an clectromagnet supported by the frame; an armaturecooperating with the electromagnet and attached to the movableelectrode; biasing means for urging the armature toward the stack; amember for transmitting motion from the biasing means to the movableelectrode adjacent thereto; a pair of insulated covered rings.

one supported by the frame and the other by the housing; a flexiblecover disposed between the frame and the housing for completelyenclosing the movable parts of the regulator, said cover having annularflange portions at each end thereof with each flange engaging one of therings to provide seals to prevent foreign matter from entering theinterior of the cover: and a resilient member having arms attached tothe interior of the cover and having a cylindrical portion engageablewith the liner to permit free movement of the liner relative to thecover.

5. An electrical regulator comprising a frame, a stack of resistancediscs supported by the frame, force applying means for compressing thestack and comprising an abutment member mounted on the frame in closecontact therewith, spring means bearing on the abutment member and meansfor transmitting force from the spring means to the stack,electromagnetic means for opposing the spring means and comprising a.magnet coil supported by the frame and an armature connected with thespring means, said force-transmittin means including a strut ofrelatively small crosssectional dimensions and relatively large heatdissipating surface area and providing for a relatively low rate oftransfer of heat from the stack to the spring means. said abutmentmember having relatively high thermal conductivity and relatlvely largearea of contact with the frame, said force-transmitting means by virtueof its ability to limit transfer of heat from the stack to the springmeans and said abutment member by virtue of its ability to extract heatfrom the spring means cooperating so to limit the temperature increaseof the spring means, in rate and amount, that the corresponding decreasein modulus of elasticity of the spring means is proportional to theincrease in resistance of the magnet coil whereby, during the warm-upperiod, variations in regulated voltage due to temperature variation areminimized.

6. An electrical regulator comprising a frame, a stack of resistancediscs supported by the frame. means for applying pressure to the stackand comprising leaf spring members, a fixed abutment member mounted onthe frame and in close contact therewith and having relatively highthermal conductivity and relatively large area of contact with theframe, and means for transmitting force from the springs to the stackand including a strut having spaced legs of relatively smallcrossserional dimensions and relatively large heat disslpating surfacearea and providing for a relatively low rate of transfer of heat fromthe stack to the springs, electromagnetic means for opposing the springsand comprising a magnet coil supported by the frame and an armatureconnected with the springs, said force-transmitting means by virtue ofits ability to limit transfer of heat from the stack to the springs andsaid abutment member by virtue of its ability to extract heat from thesprings cooperating so to limit the temperature increase of the springs,in rate and amount, that the corresponding decrease in modulus ofelasticity of the springs is proportional to the increase in resistanceof the magnet coil whereby, during the warm-up period, variations inregulated voltage due to temperature variation are minimized WILLIAM J.RADY.

